2. Integration and excitation of plasmonic structures

Due to the very different spatial extensions of plasmonic and dielectric modes, the main challenge in using plasmonics in photonic circuits is the optically "matched" integration of metal structures with dielectric guides (in the sense of electrical domain impedance matching). Integration includes a mode-transfer zone whose length depends on the interfacing mechanism. The relevant indicator for assessing the quality of the interfacing is the coupling efficiency, defined as the ratio between the power available in the plasmonic guide at the end of the transfer zone, and that in the dielectric guide before the transfer zone. This definition therefore includes losses of all kinds (ohmic, mode mismatch, etc.) generated in the transfer zone.

After a brief review of the interaction between metals and electromagnetic waves, we address these interfacing issues for the family...